1. Field
Embodiments of the invention relate to an optical recording medium, and more particularly, to a composition and a structure of a recording layer of a recordable type optical recording medium for information storage.
2. Description of the Related Art
With the advent of multimedia age comprehensively dealing with a video signal including a moving picture and a stop picture, an audio signal, and computer data information, package media including various kinds of discs such as CD and DVD have widely spread. Recently, there have been active efforts to apply an optical disc to a recording medium of a mobile phone, a digital camera, broadcasting, and a movie.
It is expected to show more remarkably such a tendency to apply the optical disc to the recording medium in the next generation media. To keep pace with such a tendency, a data transfer rate of a blu-ray disc (BD) used as the next generation media becomes greater than a current data transfer rate (i.e., 30 Mbps to 35 Mbps), a laser wavelength of the BD becomes shorter so as to achieve a high-density and large-capacity optical disc, and the size of a recording mark of the BD becomes shorter as a numerical aperture increases.
The optical recording medium may be classified into a read-only memory (ROM) disc, a recordable disc capable of recording information only once, and a rewritable disc capable of repeatedly writing, reading, and deleting information. In the ROM disc, servo, location information, or fine grooves in the form of pit are formed in a circumference direction of the ROM disc, and a reflective layer exists in the ROM disc. The recordable disc may be applied for data backup or storage of broadcasting, movie, etc.
Materials of a recording layer of the recordable disc may use an organic material such as dye or an inorganic material. The recordable disc may record through the following mechanisms: (1) a pit is generated by burning the recording materials of the recording layer, (2) as the recording materials are decomposed, a volume of the recording materials expands and results in the generation of a pit, (3) the recording layer is melted and then is solidified to thereby form a new phase, or (4) a new material (for example, silicide, germanide, and antimonide) is formed by a reaction on a contact surface between the recording materials.
Recently, in the BD, there have been continued efforts to search a recording material capable of achieving a jitter characteristic under the conditions of a wavelength of 405 nm, a recording velocity of 4.917 m/s to 29.5 m/s, and a recording power of 3 mW to 14 mW.